1. Field of the Invention
The present invention relates to a spin field effect transistor (spin FET) and a spin memory based on a new principle.
2. Description of the Related Art
In recent years, research and development have been actively made for achieving practical use of a spin electronics device utilizing a free degree of a spin of an electron. For example, a device utilizing a tunnel magneto-resistance (TMR) effect of a magnetic random access memory (MRAM) or a reproduction magnetic head of a hard disk is provided as a typical example thereof.
Recently, a spin FET has been proposed as a next generation spin device.
The spin FET has a feature that it has a magnetic recording unit that stores binary data, and is used for constituent elements such as memory cells or a re-configurable logic circuit. In the case where the logic circuit is composed of the spin FET, there is a possibility that all logics such as AND, NOR, OR, and EX-OR can be selectively achieved merely by rewriting data of a magnetic recording head of one logic circuit.
When this is achieved, there is no need for changing a layout of a transistor according to a type of a logic circuit, thus making it possible to promote significant reduction of a design/development period and significant reduction of a manufacturing cost.
Therefore, it has been studied that such a logic circuit is used in combination with a nonvolatile semiconductor memory such as a magnetic random access memory or a ferroelectric random access memory (FeRAM).
However, in a current spin FET, data is written into a magnetic recording unit by a current magnetic field (a magnetic field generated by a write current) or a spin injection current (a spin polarization electron).
Thus, in the case of using the former current magnetic field, if an element size is reduced, there occurs a problem that a value of a write current increases and power consumption increases. In the case of using the latter spin injection current, there is a need for a large current density for writing data. Thus, there occurs a reliability problem that a tunnel barrier is destructed.
Such problems occur similarly in a spin memory that carries out write/read processing by utilizing a degree of freedom of a spin of an electron as well.